Two polaroid are placed in the path of unpolarized beam of intensity I₀ such that no light is emitted from the second polaroid. If a third polaroid whose polarization axis makes an angle θ with the polarization axis of first polaroid, is placed between these polaroids then the intensity of light emerging from the last polaroid will be I₀ I₀ I
Options

Question

Two polaroid are placed in the path of unpolarized beam of intensity I₀ such that no light is emitted from the second polaroid. If a third polaroid whose polarization axis makes an angle θ with the polarization axis of first polaroid, is placed between these polaroids then the intensity of light emerging from the last polaroid will be I₀ I₀ I

Options

G1 Physics · Accepted Answer

After the first polarizer intensity is I₀/2. Through the middle polarizer it becomes (I₀/2)cos²θ. The last polarizer is crossed with the first, so it contributes sin²θ. Thus I=(I₀/2)cos²θ sin²θ=(I₀/8)sin²2θ. Hence option A.